BR102018003531A2 - vehicular power transmission system - Google Patents

Abstract

a vehicle power transmission system (16) including a locking clutch (d1) having a synchronous screen mechanism for selectively connecting and disconnecting a rotary shaft (44) having external teeth (44), and a clutch gear (54) rotatable relative to the rotary axis, in and with each other. the power transmission system including: a first piston (90) disposed within a central bore (44a) formed through the rotary shaft (44) such that the first piston is axially reciprocal; a sleeve (56) connected to the first piston, and having inner teeth (56s) engaging with the outer teeth of the rotary shaft, such that the sleeve is rotated with the rotary shaft, and such that the sleeve is axially reciprocated with the first one. piston according to the axial movement of the first piston; a synchronizer ring (78) supported in sliding contact with an outer circumferential tapered surface (54t) of the clutch gear such that the synchronizer ring is rotatable relative to the clutch gear; and an actuator (112) including a second piston (92; 200) for axially advancing the first piston to thereby bring the inner teeth of the sleeve in engagement with the clutch gear through the synchronizer ring. the first piston and the second piston are arranged coaxially with the rotary shaft.

Description

Descriptive Report of the Invention Patent for VEHICLE ENERGY TRANSMISSION SYSTEM.

FIELD OF THE INVENTION [0001] The present invention relates in general to a vehicle power transmission system, more particularly, to a vehicle power transmission system provided with a locking clutch having a synchronous screen mechanism.

BACKGROUND OF THE INVENTION [0002] A vehicle power transmission system is known including a locking clutch that has a synchronous screen mechanism, and which is configured to selectively connect and disconnect a rotary axis having external and rotatable teeth on its axis, and a rotating clutch gear relative to the rotary axis, in and between each other. JP-2016-001029A discloses an example of such a vehicle power transmission system.

SUMMARY OF THE INVENTION [0003] The locking clutch having the synchronous screen mechanism disclosed in JP-2016-001029A includes a sleeve, a displacement fork, a fork axis (transfer rail) to which the transfer fork is attached, and an actuator for operating the fork shaft for operating the fork shaft to apply a thrust force to the sleeve through the transfer fork, for movement of the sleeve in an axial direction to bring the lock clutch in its engaged state. The sleeve is reciprocated with the impulse force, in the axial direction of the rotating axis, so that the locking clutch having the synchronous screen mechanism is changed between its engaged and released states. In the JP-2016001029A lock clutch, however, the fork shaft is disposed radially externally to the rotating shaft, and the thrust force acts on the sleeve through the transfer fork that is attached to the fork shaft in one hand.

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2/36 of the cantilever, for example, so that the fork shaft is bent or deflected due to the thrust force, and a piston provided at an axial end of the fork shaft is subjected to a force in an inappropriate direction , giving rise to a risk of deterioration of an intended seal function of an oil seal seated on the piston, and consequent performance instability of the seal function of the oil seal.

[0004] The present invention was produced in view of the prior art described above. It is, therefore, an objective of the present invention, to provide a vehicle energy transmission system in which a piston to move a glove to change a lock clutch having a synchronous screen mechanism, between its engaged and released states, has a high degree of operating stability.

[0005] The above objective is achieved according to any of the following modes of the invention:

[0006] According to a first mode of the invention, a vehicle power transmission system is provided including a lock clutch having a synchronous screen mechanism, the lock clutch of which is provided to selectively connect and disconnect a rotary shaft having external teeth and rotatable about its axis, and a rotating clutch gear relative to the rotary axis, in and between each other, the clutch gear having a tapered outer circumferential surface. The vehicle energy transmission system comprises: a first piston arranged inside a central hole formed through the rotating axis, such that the first piston is axially reciprocal; a glove connected to the first piston and having internal teeth engaging with the external teeth of the rotary axis, so that the glove is rotated with the rotary axis, and such that the glove is axially reciprocal together with the first piston, according to the movements axial axles of the first piston; a synchronizer ring supported in contact

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3/36 sliding with the tapered outer circumferential surface of the clutch gear, such that the synchronizer ring is rotatable relative to the clutch gear; and an actuator including a second piston to axially reciprocate the first piston to thereby bring the inner teeth of the sleeve into engagement with the clutch gear through the synchronizer ring. The first piston and the second piston are arranged coaxially with the rotating axis.

[0007] According to a second mode of the invention, Vehicle energy transmission system, according to the first mode of the invention, additionally comprises an elastic member disposed between an outer circumferential surface of the first piston, and an inner circumferential surface of the shaft rotating to tilt the first piston in one direction to disengage the inner teeth from the sleeve from the clutch gear.

[0008] According to a third mode of the invention, Vehicle energy transmission system, according to the second mode of the invention, is configured such that the elastic member is a spiral spring arranged coaxially with the first piston.

[0009] According to a fourth mode of the invention, Vehicle power transmission system, according to the second or third mode of the invention, is configured such that the first piston is axially retracted in a distant direction from the clutch gear with a tilt force of the elastic member, while the first piston is not axially advanced by the second piston. [0010] According to a fifth mode of the invention, Vehicle power transmission system, according to any of the first to fourth modes of the invention, is configured such that the rotary axis is supported by a pair of support walls, via a pair of bearings, and the second piston is at least partially accommodated

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4/36 inside the pair of support walls.

[0011] According to a sixth mode of the invention, Vehicle power transmission system, according to the fifth mode of the invention, is configured such that the actuator is a hydraulic actuator having a piston seating hole that is formed in the above one of the pair of support walls is described coaxially with the second piston, and in which the second piston is slidably and hermetically sealed with oil, and the second piston and the piston seating hole cooperate to define an oil chamber.

[0012] According to a seventh mode of the invention, Vehicle energy transmission system, according to the sixth mode of the invention, is configured such that the oil chamber is a cylindrical space formed coaxially with the rotating axis.

[0013] According to an eighth mode of the invention, Vehicle power transmission system, according to any of the first to seventh modes of the invention, is configured such that a damping member is interposed between the first and second pistons, and the the first piston is kept in adjacent contact with the second piston, via the damping member, such that the first piston is rotatable relative to the second piston.

[0014] According to a ninth mode of the invention, Vehicle power transmission system, according to the eighth mode of the invention, is configured such that the damping member is connected to an axial end face of the second piston on the side of the first piston .

[0015] According to a tenth mode of the invention, Vehicle power transmission system, according to the sixth or seventh mode of the invention, is configured such that the hydraulic actuator includes a mechanically operated hydraulic pump, or an electrically operated hydraulic pump to pressurize an operating fluid in the oil chamber), to thereby axially move the second

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5/36 piston in one direction towards the first piston.

[0016] According to an eleventh mode of the invention, Vehicle power transmission system, according to any of the first to seventh modes of the invention, is configured such that the rotary axis has a central hole in which the first piston and an axial end portion of the second piston are accommodated, and a lubricant is supplied in the central hole through one of the opposite axial open ends of the central hole which is on the other side of the pair of support walls, the clutch gear being mounted on the shaft rotary, via a needle bearing, such that the clutch gear is rotatable relative to the rotary axis, the rotary axis having at least one radial oil passage formed so as to extend through it in its radial direction, so that the Lubricant is distributed from the central hole to the needle bearing through at least one radial oil passage.

[0017] According to an twelfth mode of the invention, Vehicle energy transmission system, according to the eleventh mode of the invention, is configured such that the rotary axis has a guide hole that extends in its axial direction, for fluid communication with the central hole, and the sleeve is connected to the first piston through a connecting member that extends through the guide hole, and which is attached to the first piston.

[0018] According to a thirteenth mode of the invention, Vehicle power transmission system, according to any of the first to twelfth modes of the invention, is configured such that the first piston is located in an axially middle portion of the axis rotary.

[0019] According to a fourteenth mode of the invention, Vehicle power transmission system, according to any of the first to twelfth modes of the invention, is configured such

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6/36 that the first piston is located on an axial end portion of the rotating shaft that is on the side of the second piston.

ADVANTAGES OF THE INVENTION [0020] According to the first mode of the invention, the vehicle energy transmission system comprises the first piston arranged inside the rotary axis in a rotating form, and the sleeve connected to the first piston and reciprocally together with the first piston in one direction of a rotary axis, according to axial movements of the first piston. The glove has internal teeth engaging with external teeth of the rotary axis so that the glove is rotated with the rotary axis. The vehicle power transmission system additionally comprises the synchronizer ring supported in sliding contact with the tapered outer circumferential surface of the clutch gear, such that the synchronizer ring is rotatable relative to the clutch gear, and the hydraulic actuator including the second piston to advance axially the first piston to thereby bring the inner teeth of the sleeve in engagement with the clutch gear through the synchronizer ring. In addition, the first piston and the second piston are arranged coaxially with the rotary axis. In this way, the locking clutch is changed from the released state to the engaged state with an axial movement of the sleeve with a thrust force that is applied to the first piston disposed inside and coaxially with the rotating axis, by an axial movement of the second piston also arranged coaxially with the rotating axis. Namely, the thrust force is applied to the rotating axis through the first and second pistons arranged coaxially with the rotating axis. Consequently, the first coaxial piston with the rotary axis is less likely to be subjected to a bending force than where the first piston receives the thrust force at a point not on the axis of the rotary axis, for example, at a point spaced at

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7/36 from the axis in the radial direction of the rotary axis. Therefore, the first piston is not required to be provided with an oil sealing member, and is operable with a high degree of stability, so that the locking clutch has an increased degree of operational reliability.

[0021] According to the second mode of the invention, the vehicle energy transmission system additionally comprises the elastic member in the form of the spiral spring disposed in the space between the outer circumferential surface of the first piston and the inner circumferential surface of the rotary axis for tilt the first piston in the axial direction to disengage the inner teeth of the sleeve from the clutch gear. Consequently, the first piston can be moved in the axial direction to disengage the inner teeth of the glove from the clutch gear with the inclination force of the elastic member.

[0022] According to the third mode of the invention, the elastic member is a spiral spring coaxially arranged with the first piston. Consequently, the first piston can be efficiently moved with the tilt force of the spiral spring in the direction to disengage the inner teeth of the sleeve from the clutch gear.

[0023] According to the fourth mode of the invention, the first piston is axially retracted in the distant direction from the clutch gear with the tilt force of the spiral spring, while the first piston is not axially advanced by the second piston. Since the first piston can be retracted in the distant direction from the clutch gear with the tilt force of the spiral spring, the vehicle power transmission system does not need to be configured to apply a hydraulic pressure from a pressurized operating fluid to the first piston to retract the first piston

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8/36 in the distant direction from the clutch gear. Consequently, the vehicle power transmission system is not required to be provided with a solenoid operated valve for applying the hydraulic pressure of the pressurized operating fluid to the first piston, so that the number of components of the vehicle power transmission system can reduced, as a result of the reduction of its production cost.

[0024] According to the fifth mode of the invention, the rotary axis is supported by the pair of support walls, via the pair of bearings, and the second piston is at least partially accommodated within one of the pair of support walls. Since the second piston for axially advancing the first piston is at least partially accommodated within the support wall separate from the rotating shaft, the rotating shaft does not need to be provided with a precisely formed portion to accommodate the second piston, and a sealing member having a high degree of sealing function. Consequently, the production cost of the rotary axis can be reduced.

[0025] According to the sixth mode of the invention, the actuator is the hydraulic actuator having the piston seating hole that is formed in the above described one of the pair of support walls coaxially with the second piston, and in which the second piston it is slidably and hermetically sealed with oil, and the second piston and the piston seating hole cooperate to define the oil chamber. When the locking clutch is brought into its engaged state, the pressurized operating fluid is fed into the oil chamber to axially move the second piston to axially advance the first piston to which the sleeve is connected. Consequently, it is not necessary to apply the hydraulic pressure of the pressurized operating fluid directly to the first piston, so it is not necessary to provide the first piston with an oil sealing member, and

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9/36 it is not necessary to form an oil passage through which the pressurized operating fluid is fed to axially advance the first piston. Consequently, the production cost of the vehicle power transmission system can be reduced.

[0026] According to the seventh mode of the invention, the oil chamber is the cylindrical space formed coaxially with the rotating axis.

[0027] Since the oil chamber is formed as the cylindrical space coax with the rotating axis, that is, coaxially with the first and second pistons, a loss of hydraulic pressure from the pressurized operating fluid to be fed into the oil chamber be made smaller than where the oil chamber was not coaxial with the first and second pistons. Consequently, the second piston can be operated with a high degree of efficiency, and the first piston can be operated with a consequently high degree of efficiency.

[0028] According to the eighth mode of the invention, the damping member is interposed between the first and second pistons, and the first piston is kept in adjacent contact with the second piston, via the damping member, such that the first piston is rotatable relative to the second piston. The damping member reduces the risk of breakage and deformation of the first and second pistons due to the impact force generated after direct adjacent contact between the first and second pistons.

[0029] According to the ninth mode of the invention, the damping member is connected to an axial end face of the second piston on the side of the first piston. This damping member, which has a simple structure connected to the second piston, makes it possible to reduce the risk of breakage and deformation of the first and second pistons due to the impact force generated after direct adjacent contact between the first and second pistons.

[0030] According to the tenth mode of the invention, the hi actuator

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Hydraulic 10/36 includes a mechanically operated hydraulic pump, or an electrically operated hydraulic pump, to pressurize the operating fluid in the oil chamber, to thereby axially move the second piston towards the first piston. The hydraulic pressure of the pressurized operating fluid can be regulated mechanically or electrically, which is functionally optimal for various types of vehicle energy transmission system design.

[0031] According to the eleventh mode of the invention, the rotary axis has the central hole in which the first piston and the axial end portion of the second piston are accommodated, and the lubricant is supplied in the central hole through the axial open end of the central hole on the side of the one described above the pair of support walls. Additionally, the clutch gear is mounted on the rotary shaft, via the needle bearing, such that the clutch gear is rotatable relative to the rotary shaft. The rotating shaft has at least one radial oil passage formed so that it extends through it in its radial direction, so that the lubricant is distributed from the central hole to the needle bearing through at least one oil passage radial. The lubricant supplied in the central hole of the rotary shaft allows the reduction of wear amounts of the rotary shaft, clutch gear, first and second pistons, and other components of the vehicle power transmission system, while the lock clutch is placed in its engaged state, for example.

[0032] According to a twelfth mode of the invention, the rotary axis has the guide hole that extends in its axial direction, for fluid communication with the central hole, and the sleeve is connected to the first piston through the connection that extends through the guide hole, and that is attached to the first piston. Since the sleeve is connected to the first piston through the connecting member, the

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11/36 sleeve is reciprocated in the axial direction of the rotary axis when the first piston is reciprocated.

[0033] According to a thirteenth mode of the invention, the first piston is located in the axially middle portion of the rotary axis. Since the first piston with which the glove is reciprocated is disposed coaxially with the rotary axis, and located in the axially middle portion of the rotary axis, the vehicle energy transmission system is applicable to a conventional MT type vehicle provided with the rotary axis , for example, without the need for complicated modification of MT vehicle components (a vehicle with a manual transmission). Therefore, the vehicle power transmission system can be simplified in construction, and produced at a reduced cost.

[0034] According to the fourteenth mode of the invention, the first piston is located on an axial end portion of the rotating shaft that is on the side of the second piston. Since the first piston and the second piston with which the sleeve is reciprocated is arranged coaxially with the rotary axis, and located in the axial end portion of the rotary axis on the side of the second piston, the vehicle energy transmission system is applicable to a conventional MT-type vehicle provided with the rotary axle, for example, without the need for complicated modification of MT-type vehicle components. In addition, the second piston can be reduced in size, so that the vehicle power transmission system can be simplified in construction, and produced at a reduced cost.

BRIEF DESCRIPTION OF THE DRAWINGS [0035] Figure 1 is a schematic view showing an arrangement of a vehicle having an energy transmission system, in accordance with an embodiment of the present invention;

[0036] Figure 2 is a view showing the transmission system

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12/36 power when a locking clutch having a synchronous screen mechanism shown in Figure 1 is placed in its engaged state;

[0037] Figure 3 is an enlarged view of a part of the locking clutch having the synchronous screen mechanism of Figure 2; and [0038] Figure 4 is a schematic view showing an arrangement of a vehicle power transmission system, according to another embodiment of this invention, when a locking clutch having a synchronous screen mechanism is placed in its engaged state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0039] Referring to the drawings, a preferred embodiment of the present invention will be described in detail. It is to be understood that the drawings are simplified and transformed as needed, and do not necessarily represent precisely the dimensions and shapes of various elements of the embodiment.

FIRST ACHIEVEMENT [0040] Figure 1 is a schematic view showing an arrangement of a vehicle 10 having an energy transmission system 16, in accordance with an embodiment of this invention. As shown in Figure 1, vehicle 10 is provided with a vehicle power source for the vehicle in the form of an engine 12, drive wheels 14, and the power transmission system 16 arranged between the engine 12 and the drive wheels 14. The energy transmission system 16 includes, inside, a stationary member in the form of a housing 18: a fluid operated energy transmission device in the form of a known torque converter 20 connected to the motor 12; an input shaft 22 connected to the torque converter 20; a continuously variable transmission mechanism in the form of a known continuously variable transmission 24 type belt and pulley (hereinafter

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13/36 hereinafter referred to as continuously variable transmission 24) connected to input shaft 22; a forward / reverse switching device 26 connected to input shaft 22; a power transmission mechanism in the form of a gear mechanism 28 connected to the input shaft 22 via the forward / reverse switching device 26, and arranged in parallel with the continuously variable transmission 24; an output shaft 30 which is a rotary output member of both the continuously variable transmission 24 and the gear mechanism 28; a counter axis 32; a speed reduction gear device 34 consisting of a pair of interlocking gears, which are respectively rotated with the output shaft 30 and the counter shaft 32; a differential gear device 38 connected to the counter shaft 32, such that a differential gear 36 of the differential gear device 38 is rotated with the counter shaft 32; and a pair of axles 40 connected to the differential gear device 38. In the power transmission system 16 constructed as described above, a driving force, energy or torque, generated by the motor 12 is transmitted to the pair of driving wheels 14 through the torque converter 20, continuously variable transmission 24, or forward / reverse gear 26, and gear mechanism 28, speed reduction gear device 34, differential gear device 38, and shafts 40 .

[0041] As described above, the energy transmission system 16 is provided with the continuously variable transmission 24 and the gear mechanism 28, which are arranged in parallel with each other, between the motor 12 (or the input shaft 22 which is a rotating input member that receives the driving force of the motor 12) and the driving wheels 14 (or the output shaft 30 which is a rotating output member of which the driving force of the motor 12 is

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14/36 transmitted to the drive wheels 14). In this way, the energy transmission system 16 has a first energy transmission path through which the driving force of the motor 12 is transmitted through the continuously variable transmission 24 from the input shaft 22 to the driving wheels 14 (i.e. ie, for the output shaft 30), and a second energy transmission path through which the driving force of the motor 12 is transmitted through the gear mechanism 28 from the input shaft 22 to the driving wheels 14 (i.e. is, for the output shaft 30). In the power transmission system 16, one of the first and second power transmission paths is selectively placed in a power transmission state depending on a vehicle operating state 10. The power transmission system 16 is provided with clutches for selectively place the first and second energy transmission paths in the energy transmission state. Namely, the power transmission system 16 is provided with a first clutch in the form of a CVT C2 drive clutch for placing the first power transmission path in the power transmission state or a voltage cut-off state, and a second clutch in the form of a forward drive clutch C1 and a reverse drive brake BI for placing the second path of power transmission in the power transmission state, or a voltage cut-off state. The CVT drive clutch C2, the forward drive clutch C1 and the reverse drive brake BI are power connection / disconnection devices, each of which is a hydraulically operated friction coupling device (friction clutch) that is placed in a state engaged by a hydraulic actuator. The forward drive clutch C1 and the reverse drive brake BI are elements of the

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15/36 forward / reverse 26 which will be described in detail.

[0042] The torque converter 20 is disposed radially externally, and coaxially with the input shaft 22, and is provided with a pump impeller 20p connected to the motor 12, and a turbine impeller 20t connected to the input shaft 22. A mechanically operated hydraulic pump 41 is connected to the pump impeller 20p, and is operated by a rotary movement of the pump impeller 20p driven by the motor 12, to generate a pressurized operating oil used to change a continuously variable transmission speed ratio 24 , to tension the transmission belt 70 of the continuously variable transmission 24, to selectively place the above-described clutches C1 and C2 and brake BI in their engaged and released states, and to lubricate various portions of the energy transmission system 16.

[0043] The forward / reverse switching device 26 is arranged in the second energy transmission path described above, radially externally from, and coaxially with the input shaft 22, and consists mainly of a 26p planetary gear assembly. a type of double pinion, the advance drive clutch C1 and the reverse drive brake B1. The planetary gear assembly 26p is a differential mechanism including three rotating elements, that is, a rotating input element in the form of a conveyor 26c, a rotating output element in the form of a solar gear 26s, and a rotating reaction element in the shape of a 26r ring gear. The conveyor 26c is integrally connected to the input shaft 22, and the ring gear 26r is selectively fixed to the housing 18 via the reverse drive brake B1, while the solar gear 26s is attached to a small diameter gear 42 which is arranged radially externally from, and coaxially from the input shaft 22, such that the engine

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16/36 solar nage 26s is rotatable relative to input shaft 22. Conveyor 26c and solar gear 26s are selectively connected to each other via the advance drive clutch C1. Namely, the advance drive clutch C1 functions as a clutch mechanism configured to selectively connect two rotating elements of the three rotating elements of the 26p planetary gear assembly, while the reverse drive brake B1 functions as a clutch mechanism configured for selectively fix the rotary reaction element of the planetary gear assembly 26p to housing 18.

[0044] The continuously variable transmission 24 is arranged on an energy transmission path between the input shaft 22 and the output shaft 30. The continuously variable transmission 24 is provided with a primary pulley 64 fixedly mounted on the input shaft 22, a secondary pulley 68 fixedly mounted on a rotating shaft 66 disposed coaxially with the output shaft 30, and the above-mentioned drive belt 70 that connects the secondary primary pulleys 64 and 68. A driving force is transmitted between the secondary primary pulleys 64 and 66 through the frictional forces between the transmission belt 70 and the pulleys 64 and 68. An effective diameter of each of the pulleys 64 and 68, which is defined by the V-groove widths of the pulleys 64 and 68 for engagement with the belt transmission speed 70, is variable so that a speed ratio (gear ratio) v of the continuously variable transmission 24 (= an input shaft speed N i / an output shaft speed No), is variable. The CVT C2 drive clutch is arranged on one of the opposite sides of the continuously variable transmission 24 which is on the side of the drive wheels 14, that is, arranged between the secondary pulleys 68 and the output shaft 30, to selectively connect and disconnect the secondary pulley 68 (rotating shaft 66), and the output shaft 30

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17/36 in and between each other. In the energy transmission system 16, an energy transmission path is established in the first energy transmission path described above, to transmit the driving force from the motor 12 to the output shaft 30 through the input shaft 22 and the transmission continuously variable 24 when the CVT C2 drive clutch is placed in the engaged state. In the energy transmission system 16, the first energy transmission path is placed in a neutral state (voltage cut-off state) when the CVT C2 drive clutch is placed in the released state.

[0045] The gear mechanism 28 is provided with a small-diameter gear 42, and a large-diameter gear 46 engaging with the small-diameter gear 42. The large-diameter gear 46 is mounted on a rotary axis 44 rotatable about its axis, namely, a counter axis of the gear mechanism 44, such that the large diameter gear 46 is rotated with the counter axis of the gear mechanism 44 on its axis C1. The gear mechanism 28 is additionally provided with an intermediate gear 48 coaxially mounted on the counter axis of the gear mechanism 44, such that the intermediate gear 48 is rotatable relative to the counter axis of the gear mechanism 44, and an output gear 50 coaxially. mounted on the output shaft 30, such that the output gear 50 is rotated with the output shaft 30. The output gear 50 is held in locking engagement with the intermediate gear 48, and has a larger diameter than the intermediate gear 48. In this way, the gear mechanism 28 is an energy transmission mechanism that is arranged between the input shaft 22 and the output shaft 30, and which has a predetermined gear ratio. A D1 lock clutch having a synchronous screen mechanism (from

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18/36 hereinafter referred to as locking clutch D1) is arranged coaxially with the counter shaft of the gear mechanism 44, and between the large diameter gear 46 and the intermediate gear 48 in the axial direction of the counter shaft of the gear mechanism 44 , to selectively connect and disconnect large diameter gear 46 and intermediate gear 48 in and between each other. The D1 lock clutch is a lock type clutch that is provided in the power transmission system 16 (arranged in a power transmission path between the motor 12 and the drive wheels 14), to selectively place an energy transmission path between the solar gear 26s and the output shaft 30, in a state of power transmission and a state of voltage cut. Locking clutch D1 functions as a third clutch that is arranged between the advance drive clutch C1 and the output shaft 30, to selectively place the second energy transmission path described above in the energy transmission state or cut-off state .

[0046] Figure 2 is the view showing the power transmission system 16 when the lock clutch D1 shown in Figure 1 is placed in its engaged state. As shown in Figure 2, the counter axis of the gear mechanism 44 is rotatably supported on its C axis, by a pair of support walls 82a and 82b, via respective bearings 80a and 80b. The counter axis of the gear mechanism 44 has a central hole 44a having the C axis, and is lubricated with a lubricant supplied in the central hole 44a through its opposite axial open ends on the side of the support wall 82a, while the counter axis of the gear mechanism 44 is supported by the support wall pair 82a and 82b.

[0047] Described more specifically by reference to Figure 2, the D1 lock clutch includes a 54 clutch gear

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19/36 which is fixed to or integrally formed with an axial end portion of the intermediate gear 48 on the side of the large diameter gear 46, coaxially with the counter axis of the gear mechanism 44, such that the clutch gear 54 is rotatable relative to the counter axis of gear mechanism 44. This clutch gear 54 functions as one of a pair of mutually engaging gears of lock clutch D1. Locking clutch D1 additionally includes a sleeve 56 attached to a first piston 90 with a fixing member in the form of a connecting pin 58. The first piston 90 is disposed within the central hole 44a of the counter shaft of the gear mechanism 44. Glove 56 has internal teeth 56s (described below) engaging with external teeth 44 of the counter shaft of gear mechanism 44. Glove 56 is mounted on the counter shaft of gear mechanism 44, such that glove 56 is rotated with the counter shaft of the gear mechanism 44 on the C axis, and it is movable relative to the counter axis of the gear mechanism 44 in the direction of the C axis. The internal teeth 56s of the sleeve 56 which are interlockable with the clutch gear 54 to engage with the gear of clutch 54 functions like the other of the above mentioned mutually engaging pair of locking clutch D1. Locking clutch D1 additionally includes a needle bearing 84 interposed between the counter shaft of gear mechanism 44, and clutch gear 54 and intermediate gear 48 in its radial direction, so that clutch gear 54 and intermediate gear 48 are supported by or mounted on the counter shaft of gear mechanism 44, via needle bearing 84, such that clutch gear 54 and intermediate gear 48 are rotatable relative to the counter shaft of gear mechanism 44. The counter shaft of gear mechanism 44 has passages from

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20/36 radial oils 86 formed to extend through them in their radial direction, so that the lubricant supplied in the central hole 44a through its axial open end on the side of the support wall 82a is distributed from the central hole 44a for the needle bearing 84 through the radial oil passages 86.

[0048] Figure 3 is an enlarged view of part of the D1 lock clutch. As shown in Figure 3, the locking clutch D1 has a synchronization mechanism in the form of a synchronous screen mechanism SI known for synchronizing the rotational speeds of the sleeve 56 and the clutch gear 54 after their engagement with each other. Figure 3 shows the D1 lock clutch placed in its released state in which the second energy transmission path is placed in the voltage cut-off state, more specifically, while the inner teeth 56s formed on an inner circumferential surface 56 of the glove. 56 are not kept in snap engagement with outer teeth 54s of clutch gear 54. The synchronous screen mechanism SI has a synchronizer ring 78, and clutch gear 54 has a tapered outer circumferential surface 54t that is provided for sliding contact with the synchronizer ring 78, and an outside diameter of which decreases in the axial direction from the intermediate gear 48 towards the large diameter gear 46, after the gear mechanism 28 is mounted in position. The synchronizer ring 78 is supported in sliding contact with the tapered outer circumferential surface 54t such that the synchronizer ring 78 is rotatable relative to the counter axis of gear mechanism 44. When sleeve 56 is axially moved from its position in Figure 3 towards clutch gear 54, the inner teeth 56s of the sleeve 56 come in adjacent contact with the outer teeth 78s of the synchronizer ring 78 of the synchronous screen mechanism S1, so that the

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21/36 axial movement of the sleeve 56 is prevented by the adjacent contact, whereby the synchronization of the rotational movements of the sleeve 56 and the clutch gear 54 with each other is initiated. As a result of the synchronization of the rotational movements of the sleeve 56 and the clutch gear 54, the inner teeth 56s of the sleeve 56 are brought into engagement with the outer teeth 54s of the clutch gear 54, via the outer teeth 78s of the synchronizer ring. 78. As a result of the interlocking engagement of the inner teeth 56s of the sleeve 56 with the outer teeth 54s of the clutch gear 54, the latch clutch D1 is brought into its engaged state, so that the second energy transmission path above described is switched from its cut-off state to its power transmission state. As shown in Figures 2 and 3, the sleeve 56 has a radial hole 56a through which the connecting pin 58 and a bushing 60 extend. Connecting pin 58 extends through bushing 60.

[0049] As shown in Figure 2, the first piston 90 has a first cylindrical portion 90a, and the counter axis of the gear mechanism 44 has a guide hole 88 in which the connecting pin 58 and the bushing 60 are fixed to the first portion cylindrical 90a, in order to extend in its radial direction, are allowed to move in the direction of the C axis. The guide hole 88 is drilled in the outer circumferential surface of the counter axis of the gear mechanism 44, and is formed so that it extend in the radial direction of the counter shaft of the gear mechanism 44, for communication with the central hole 44a, but do not extend across a total diameter of the counter shaft of the gear mechanism 44. The guide hole 88 has a dimension in the direction of the CO axis connecting pin 58 that extends through the guide hole 88 together with the bushing 60 is fixed in its head portion to the sleeve 56, so that the sleeve 56 is reciprocated together

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22/36 with the first cylindrical portion 90a of the first piston 90.

[0050] In the D1 lock clutch, the first piston 90 is axially reciprocated by a second piston 92 and a spiral spring 96 (described below), so that sleeve 56 attached to the first piston 90 is reciprocated (forward and retracted) in direction of the C axis of the counter axis of the gear mechanism 44, whereby the lock clutch D1 is switched between its released and engaged states. In the vehicle energy transmission system 16, the second energy transmission path is placed in the energy transmission state for transmission of the driving force of the motor 12 from the input shaft 22 to the output shaft 30, through the mechanism gear 28 to drive vehicle 10 in forward or reverse direction, when lock clutch D1 and forward drive clutch C1, or reverse drive brake B1 are both placed in their engaged states. On the other hand, the second energy transmission path is placed in the voltage cut or neutral state, when the forward drive clutch C1 and the reverse drive brake B1 are both placed in their released states, or when at least the clutch D1 lock is placed in its released state.

[0051] As shown in Figure 2, the first piston 90 and an axial end portion of the second piston 92 adjacent to the first piston 90, are accommodated inside the central hole 44a which is formed through the counter axis of the gear mechanism 44, and that has different diameters. The first and second pistons 90 and 92 are arranged coaxially with the counter axis of the gear mechanism 44. As shown in Figure 2, the first piston 90 is located in an axially intermediate or middle portion of the central hole 44a, that is, in an axially intermediate or middle portion of the counter axis of gear mechanism 44. The

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The first piston 90 is a staggered solid cylindrical member consisting of the first cylindrical portion 90a, and a second cylindrical portion 90b having a smaller diameter than the first cylindrical portion 90a. The first cylindrical portion 90a is located on the side of the second piston 92, while the second cylindrical portion 90b is located on one side of the first remote cylindrical portion 90a of the second piston 92. One of the opposite axial end faces of the first piston 90 which is remote from the second piston 92, that is, an axial end face of the second cylindrical portion 90b abuts against a shoulder surface 44b of the counter axis of the gear mechanism 44 perpendicular to the axis C, which is a shoulder surface of the counter axis of the gear mechanism 44 which partially defines the central hole 44a. The first cylindrical portion 90a has a fixing hole 94 formed in its radial direction, so as to be opened in its outer circumferential surface, and each of the connecting pin 58 and the bushing 60 is fixed in its axial end portion in the fixing hole. 94, by pressure fitting, for example, so that the first piston 90 and the sleeve 56 are connected or fixed together with the connecting pin 58 and the bushing 60. While the connecting pin 58 is used as a member connecting bolts for connecting the first piston 90 and the sleeve 56 in a present embodiment, a connecting bolt can be used as the connecting member, for example. In this example, the first cylindrical portion 90a has a tapered bore formed on its outer circumferential surface.

[0052] An elastic member in the form of the spiral spring 96 indicated above is disposed radially externally of the second cylindrical portion 90b. More specifically described, the spiral spring 96 is accommodated in a space formed between the second cylindrical portion 90b and an internal circumferential surface 44c of the counter axis of the gear mechanism 44 that partially defines the central hole 44a, the

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24/36 namely, in a cylindrical space defined by the outer circumferential surface of the second cylindrical portion 90b, the shoulder surface 44b, and the inner circumferential surface 44c of the counter axis of the gear mechanism 44. The spiral spring 96 is arranged coaxially with the first piston 90, that is, coaxially with the counter axis of gear mechanism 44. The first piston 90 is moved axially with a tilt force of the spiral spring 96 in a direction away from the clutch gear 54, while the first piston 90 it is not axially advanced by the second piston 92 in a direction towards the clutch gear 54, namely, in the left direction, as seen in Figure 2. Described in more detail, the first piston 90 is kept away from the shoulder surface 44b under a tilt action of the spiral spring 92, while a hydraulic pressure of a pressurized operating fluid described below does not is applied to the second piston 92, and thus the piston is not driven towards the clutch gear 54, that is, while an oil chamber 102 which is formed in the support wall 82b, and in which an end portion axial of the second piston 92 remote from the first piston 90 is slidably seated and is not loaded with the pressurized operating fluid. In this regard, it is noted that the oil chamber 102 and the second piston 92 function as a hydraulic actuator 112.

[0053] As shown in Figure 2, the second piston 92 consists of a cylindrical main body portion 92a, and a collar portion 92b which is a member generally similar to the disc. An axial end portion of the second piston 92 on the side of the first piston 90, i.e., an axial end section of the main body portion 92a on the side of the first piston 90 is accommodated within the central bore 44a, while the other axial end portion of the second piston 92, that is, the collar portion 92b is accommodated within the support wall

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25/36

82b, such that collar portion 92b cooperates with support wall 82b to define oil chamber 102. More specifically described, collar portion 92b, which is a separate member from main body portion 92a, is slidably and seated oil-tight in a piston seating hole 100 formed in the support wall 82b coaxially with the second piston 92, such that the collar portion 92b and piston seating hole 100 cooperate to define the oil chamber 102. The collar collar 92b is provided with a sealing member in the form of an O-ring 104, for example. The oil chamber 102 is a cylindrical space formed coaxially with the counter axis of the gear mechanism 44 having the C axis, and is maintained in fluid communication with an oil passage 106 formed through the support wall 82b, so that the operating fluid, the hydraulic pressure from which it is regulated, is fed into oil chamber 102 through oil passage 106. When the pressurized operating fluid is fed into oil chamber 102, the second piston 92 is axially moved or advanced in towards the first piston 90, for adjacent contact with the first piston 90, such that the first piston 90 is rotatable relative to the second piston 92. A damping member 110 is integrally bonded with an adhesive to an axial end face of the main body portion 92a the second piston 92, which is on the side of the first piston 90. For example, the damping member 110 takes the form of a disk. One of the opposing surfaces of the remote damping member 110 of the above-indicated axial end face of the main body portion 92a is abutment against an axial end face of the first piston 90, which is on the side of the second piston 92. The collar portion 92b is fixed to the main body portion 92a with a fixing member in the form of a fixing screw 108, for example. While the operating fluid is pressurized by the mechanically operated hydraulic pump 41 in this embodiment, the

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26/36 operating fluid can be prepared electrically, for example. [0054] In a present embodiment, the D1 lock clutch is switched from its released state to its engaged state by applying a thrust force to the first piston 90, via the second piston 92, to axially move the sleeve 56 to bring its inner teeth 56s in engagement with the outer teeth 54s of the clutch gear 54 through the outer teeth 78s of the synchronizer ring 78. More specifically, the thrust force is applied to the first piston 90, via the second piston 92 by mechanical means , namely, by the adjacent contact of the second piston 92 with the first piston 90 with an axial movement of the second piston 92 with the hydraulic pressure of the pressurized operating fluid fed in the oil chamber 102, without applying the hydraulic pressure directly to the first piston 90 Since the first piston 90 is driven by mechanical means without directly applying hydraulic pressure to it, the first piston so 90 is not required to be provided with any oil sealing member, and the central hole 44a and the first piston 90 are not required to be formed with a high degree of precision of their diametric dimensions in order to avoid a problem of the so-called adhesion of the first piston 90 within the central hole 44a, which would occur when the counter axis of the gear mechanism 44 is deformed due to a load received from the associated gears. In addition, an oil passage for applying the hydraulic pressure of the pressurized operating fluid directly to the first piston 90 is not required, and the first piston 90 does not suffer from a slip loss problem due to the provision of the oil sealing member above indicated. The first piston 90 is advanced with the axial movement of the second piston 92 to adjacent contact with the first piston 90, and is returned or retracted back to the original position with the tilt force of the spiral spring 96. Namely, the present

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27/36 embodiment is configured to reciprocate the first piston 90 in the direction of the C axis, with the mechanical means.

[0055] The vehicle power transmission system 16, according to the present first embodiment of the invention described above, comprises the first piston 90 disposed within the rotary axis in the form of the counter axis of the gear mechanism 44, and the sleeve 56 connected to the first piston 90 and reciprocated together with the first piston 90 in the direction of the C axis of the counter axis of the gear mechanism 44, according to the axial movements of the first piston 90. The sleeve 56 has the inner teeth 56s engaging with the teeth external 44 of the counter axis of the gear mechanism 44, so that the sleeve 56 is rotated with the counter axis of the gear mechanism 44. The vehicle power transmission system 16 additionally comprises the synchronizer ring 78 supported in sliding contact with the surface tapered outer circumference 54t of clutch gear 54, such that the synchronizer ring 78 is rotatable relative to clutch gear 54, and the actuator hydraulic 112 including the second piston 92 to axially reciprocate the first piston 90 to thereby bring the inner teeth 56s of the sleeve 56 in engagement with the clutch gear 54 through the synchronizer ring 78. Additionally, the first piston 90 and the second piston 92 are arranged coaxially with the counter axis of the gear mechanism 44. In this way, the locking clutch D1 is switched from the released state to the engaged state with an axial movement of the sleeve 56 with a thrust force that is applied to the first piston 90 disposed inside and coaxially with the counter axis of the gear mechanism 44, by an axial movement of the second piston 92 also disposed coaxially with the counter axis of the gear mechanism 44. Namely, the thrust force is applied to sleeve 56 through the first and second steps

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28/36 points 90 and 92 arranged coaxially with the counter axis of the gear mechanism 44. Consequently, the first piston 90 coaxial with the counter axis of the gear mechanism 44 is less likely to be subjected to a bending force than where the first piston 90 receives the thrust force at a point not on the C axis of the counter axis of the gear mechanism 44, for example, at a point away from the C axis in the radial direction of the counter axis of the gear mechanism 44. Therefore, the first piston 90 is not required to be provided with an oil sealing member, and is operable with a high degree of stability, so that the D1 lock clutch has a decreased degree of operational reliability.

[0056] The vehicle power transmission system 16 of the present embodiment further comprises the elastic member in the form of the spiral spring 96 disposed in the space between the outer circumferential surface of the first piston 90, and the inner circumferential surface 44c of the counter axis of the mechanism gear 44 to tilt the first piston 90 in the axial direction to disengage the inner teeth 56s from sleeve 56 of clutch gear 54. Consequently, the first piston 90 can be moved by the tilt force of spiral spring 96 with sleeve 56, in the axial direction for disengaging the inner teeth 56s from the sleeve 56 from the clutch gear 54.

[0057] The present embodiment is further configured such that the spiral spring 96 is arranged coaxially with the first piston 90. Consequently, the first piston 90 can be efficiently moved with the tilt force of the spiral spring 96 in the direction for disengaging the internal teeth. 56s of clutch gear sleeve 56.

[0058] The present embodiment is also configured such that the

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29/36 the first piston 90 is axially retracted in the distant direction of the clutch gear 54 with the tilt force of the spiral spring 96, while the first piston 90 is not axially advanced by the second piston 92. Since the first piston 90 can be retracted in the distant direction of the clutch gear 54 with the tilt force of the spiral spring 96, the vehicle power transmission system 16 does not need to be configured to apply a hydraulic pressure from the pressurized operating fluid to the first piston 90 to retract the first piston 90 in the distant direction of the clutch gear 54. Consequently, the vehicle power transmission system 16 is not required to be provided with a solenoid operated valve for applying the hydraulic pressure of the pressurized operating fluid to the first piston 90, so that the number of components of the vehicle power transmission system 16 can be re reduced, as a result of the reduction in its production cost.

[0059] The present embodiment is additionally configured such that the counter axis of the gear mechanism 44 is rotatably supported by the pair of support walls 82a and 82b, via the pair of bearings 80a and 80b, and the second piston 92 is at least partially accommodated within the support wall 82b. Since the second piston 92 for axially advancing the first piston 90 is at least partially accommodated within the support wall 80b separate from the counter shaft of the gear mechanism 44, the counter shaft of the gear mechanism 44 need not be provided with a portion precisely formed to accommodate the second piston 92, and a sealing member having a high degree of sealing function. Consequently, the production cost of the counter shaft of the gear mechanism 44 can be reduced.

[0060] The present embodiment is additionally configured as

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30/36 that the hydraulic actuator 112 has the piston seating hole 100 which is formed in the support wall 82b of the pair of support walls 82a and 82b coaxially with the second piston 92, and in which the second piston 92 is slidably and oil-tight seated, and second piston 92 and piston seating hole 100 cooperate to define oil chamber 102. When lock clutch D1 is brought in its engaged state, pressurized operating fluid is fed into the oil chamber oil 102 to axially move the second piston 92 to axially advance the first piston 90 to which the sleeve 56 is connected. Consequently, it is not necessary to apply the hydraulic pressure of the pressurized operating fluid directly to the first piston 90, so it is not necessary to provide the first piston 90 with an oil sealing member, and it is not necessary to form an oil passage through which the pressurized operating fluid is fed to axially advance the first piston 90. Consequently, the production cost of the vehicle power transmission system 16 can be reduced. In addition, the elimination of a need to provide the first piston 90 with the oil sealing member makes it possible to reduce a risk of generating a slip loss problem of the first piston 90 due to the provision of the oil sealing member, by that efficient energy transmission of the vehicle power transmission system 16 can be improved.

[0061] The present embodiment is additionally configured such that the oil chamber 102 is the cylindrical space formed coaxially with the counter axis of the gear mechanism 44. Since the oil chamber 102 is formed as the cylindrical space coax with the counter axis of the gear mechanism 44, that is, coaxially with the first and second pistons 90 and 92, a loss of hydraulic pressure from the pressurized operating fluid to be fed into the chamber

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31/36 oil ratio 102 can be made smaller than where oil chamber 102 was not coaxial with the first and second pistons 90 and 92. Consequently, the second piston 92 can be operated with a high degree of efficiency, and the first piston 90 can be operated with a consequently high degree of efficiency.

[0062] The present embodiment is additionally configured such that the damping member 110 is interposed between the first and second pistons 90 and 92, and the first piston 90 is maintained in adjacent contact with the second piston 92, via the damping member 110, such that the first piston 90 is rotatable relative to the second piston 92. The damping member 110 reduces a risk of breakage and deformation of the first and second pistons 90 and 92 due to an impact force generated after direct adjacent contact between the first and second pistons 90 and 92.

[0063] The present embodiment is further configured such that the damper member 110 is connected to an axial end face of the second piston 92 on the side of the first piston 90. This damper member 110, which has a simple structure connected to the second piston 92, makes It is possible to reduce the risk of breakage and deformation of the first and second pistons 90 and 92 due to the impact force generated after direct adjacent contact between the first and second pistons 90 and 92.

[0064] The present embodiment is additionally configured such that the hydraulic actuator 112 includes the mechanically operated hydraulic pump 41 to pressurize the operating fluid in the oil chamber 102, to thereby axially move the second piston 92 towards the first piston 90. The hydraulic pressure of the pressurized operating fluid can be regulated mechanically or electrically, which is functionally optimal for various types of vehicle power transmission system design 16.

[0065] The present embodiment is additionally configured such

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32/36 that the counter axis of the gear mechanism 44 has the central hole 44a in which the first piston 90 and the axial end portion of the second piston 92 adjacent to the first piston 90 are accommodated, and the lubricant is supplied in the central hole 44a through of the axial open end of the central hole 44a on the side of the support wall 82a. Additionally, the clutch gear 54 is mounted on the counter shaft of the gear mechanism 44, via the needle bearing 84, such that the clutch gear 54 is rotatable relative to the counter shaft of the gear mechanism 44. The counter shaft of the gear mechanism gear 44 has radial oil passages 86 formed so as to extend through it in its radial direction, so that the lubricant is distributed from central hole 44a to needle bearing 84 through radial oil passages 86. The lubricant supplied in the central hole 44a of the gear shaft counter shaft 44 allows for the reduction of the wear amounts of the gear shaft counter shaft 44, clutch gear 54, first and second pistons 90 and 92, and other components of the transmission system vehicle power 16, while the D1 lock clutch is placed in its engaged state, for example.

[0066] The present embodiment is additionally configured such that the counter axis of the gear mechanism 44 has the guide hole 88 that extends in its axial direction, for fluid communication with the central hole 44a, and the sleeve 56 is connected to the first piston 90 through the connecting member in the form of the connecting pin 58 which extends through the guide hole 88, and which is attached to the first piston 90. Since sleeve 56 is connected to the first piston 90 via the connecting pin 58, the sleeve 56 is reciprocated in the direction of the C axis of the counter axis of the gear mechanism 44 when the first piston 90 is reciprocated.

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33/36 [0067] The present embodiment is further configured such that the first piston 90 is located in the axially middle portion of the counter axis of the gear mechanism 44. Since the first piston 90 with which the sleeve 56 is reciprocated is arranged coaxially with the counter axis of the gear mechanism 44, and located in the axially middle portion of the counter axis of the gear mechanism 44, the vehicle power transmission system 16 is applicable to a conventional MT-type vehicle provided with the counter axis of the gear mechanism gear 44, for example, without the need for complicated modification of MT vehicle components. Therefore, the vehicle power transmission system 16 can be simplified in construction and produced at a reduced cost.

SECOND EMBODIMENT [0068] In the following, another embodiment of this invention will be described.

[0069] It is to be understood that the same reference signals as used in the first embodiment will be used in the following embodiment, to identify the corresponding elements, which will not be described redundantly.

[0070] Figure 4 is a schematic view showing an arrangement of the vehicle power transmission system 16, according to another embodiment of this invention, when the lock clutch D1 having the synchronous screen mechanism is placed in its engaged state. In the present second embodiment, the first piston 90, and an axial end portion of a second piston 200 which is on the side of the first piston 90, are accommodated inside the central hole 44a formed in the counter axis of the gear mechanism 44, such that the the first piston 90 and the second piston 200 are arranged coaxially with the counter axis of the gear mechanism 44 having the C axis. The first piston 90 is located in an axial end portion of the

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34/36 central hole 44a, which is on the side of the support wall 82b, namely, on the side of the second piston 200, such that the first piston 90 is reciprocated in the direction of the counter axis of the gear mechanism 44. The second piston 200 is slidably and oil-tight seated in the seating hole of piston 100 formed in the support wall 82b, and cooperates with the seating hole of piston 100 to define oil chamber 102, which cooperates with second piston 200 to define the hydraulic actuator 112. In the locking clutch D1, the first piston 90 is advanced by the second piston 200 with the pressurized operating fluid fed into the oil chamber 102, so that sleeve 56 connected to the first piston 90 is advanced in the direction of the axis C, so that the D1 lock clutch is changed from its released state to its engaged state. In the present second embodiment in which the first piston 90 is disposed in the axial end portion of the central hole 44a on the side of the support wall 82b, the axial dimension of the second piston 200 can be made smaller than that of the second piston 92 in the first embodiment, so that the latch clutch D1 has a comparatively small axial dimension.

[0071] In the present second embodiment described, the first piston 90 is located on an axial end portion of the counter shaft of the gear mechanism 44 which is on the side of the second piston 200. Since the first piston 90 with which the sleeve 56 is reciprocated is arranged coaxially with the counter axis of the gear mechanism 44, and located in the above-indicated axial end portion of the counter axis of the gear mechanism 44, the vehicle power transmission system 16 is applicable to conventional MT type vehicle provided with the axis gear mechanism counter 44, for example, without the need for complicated modification of MT vehicle components. In addition, the second piston 200

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35/36 can be reduced in size, so that the vehicle power transmission system 16 can be simplified in construction and produced at a reduced cost.

[0072] While preferred embodiments of the present invention have been described in detail with reference to the drawings, it is to be understood that the invention can otherwise be realized.

[0073] In the first illustrated embodiment, the second piston 92 is arranged so as to be partially located within the support wall 82b of the pair of support walls 82a and 82b. However, this arrangement is not essential, provided that the counter axis of the gear mechanism 44 extends between two support members.

[0074] In the illustrated embodiments, the spiral spring 96 is used as an elastic member, a tilt force of which it acts on the first piston 90 to return the first piston 90 back to its original position. However, the spiral spring 96 can be replaced by any other elastic member, such as a mechanism configured to move the first piston 90 to its original position by adding force to it.

[0075] In the illustrated embodiments, hydraulic actuator 112 is used to move the second piston. However, hydraulic actuator 112 can be replaced by an electrically operated actuator including an electric motor which is operated to rotate a pinion which is kept in engagement with a support member corresponding to the second piston.

[0076] While the preferred embodiments of the present invention and its modifications have been described for illustrative purposes only, it is to be understood that the invention can be realized with various other changes and improvements that may occur to those skilled in the art.

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NOMENCLATURE OF REFERENCE SIGNS [0077] 16: Vehicle power transmission system [0078] 44: Gear mechanism counter shaft (rotary axis) [0079] 44a: Central hole [0080] 44- External teeth of the counter shaft of the gear mechanism [0081] 54: Clutch gear (One of the fitting gear pair) [0082] 54t: Tapered outer circumferential surface [0083] 56: Sleeve [0084] 56s: Inner teeth of the sleeve (the other in the pair plug-in gearbox) [0085] 58: Connecting pin [0086] 78: Synchronizer ring [0087] 80a, 80b: Bearing pair [0088] 82a, 82b: Support wall pair [0089] 84: Needle roller [0090] 86: Radial oil passages [0091] 88: Guide bore [0092] 90: First piston [0093] 92: Second piston [0094] 96: Spiral spring (elastic member) [0095] 100: Bore hole piston [0096] 102: Oil chamber [0097] 110: Damping member [0098] 112: Hydraulic actuator (Actuator) [0099] D1: Locking clutch having a synchronous screen mechanism [00100] C: Axis

Claims (14)

1. Vehicle power transmission system (16) including a locking clutch (D1) having a synchronous screen mechanism, the locking clutch of which is provided to selectively connect and disconnect a rotary shaft (44) having external teeth (44), and a rotating clutch gear (54) relative to the rotary axis, in and between each other, the clutch gear having a tapered outer circumferential surface (54t), the vehicle power transmission system characterized by the fact that it comprises: a first piston (90) disposed within a central hole (44a) formed through the rotary axis (44), such that the first piston is axially reciprocal; a sleeve (56) connected to the first piston, and having internal teeth (56s) fitting with the external teeth of the rotating shaft so that the sleeve is rotated with the rotating shaft, and such that the sleeve is axially reciprocated together with the first piston according to axial movements of the first piston; a synchronizer ring (78) supported in sliding contact with the tapered outer circumferential surface (54t) of the clutch gear (54), such that the synchronizer ring is rotatable relative to the clutch gears; and an actuator (112) including a second piston (92; 200) to axially advance the first piston (90) to thereby bring the inner teeth (56s) of the sleeve (56) into engagement with the clutch gear (54) through the synchronizer ring (78), and in which the first piston (90) and the second piston (92; 200) are arranged coaxially with the rotary axis (44). 2. Vehicle energy transmission system, according to claim 1, characterized by the fact that it additionally comprises an elastic member (96) disposed between a cirPetition surface 870180014596, of 02/23/2018, p. 93/121 2/4 outer circumferential of the first piston (90), and an inner circumferential surface (44c) of the rotating shaft (44) to tilt the first piston in one direction to disengage the inner teeth (56s) from the sleeve (56) from the clutch gear (54). 3. Vehicle energy transmission system, according to claim 2, characterized by the fact that the elastic member is a spiral spring (96) coaxially arranged with the first piston (90). 4. Vehicle power transmission system according to claim 2 or 3, characterized in that the first piston (90) is axially retracted in a direction away from the clutch gear (54) with a tilt force of the member elastic (96), while the first piston is not axially advanced by the second piston (92; 200). Vehicle power transmission system according to any one of claims 1 to 4, characterized by the fact that the rotary axis (44) is supported by a pair of support walls (82a, 82b), via a pair of bearings (80a, 80b), and the second piston (92; 200) is at least partially accommodated within one (82b) of the pair of support walls. 6. Vehicle power transmission system, according to claim 5, characterized by the fact that the actuator is a hydraulic actuator (112) having a piston seating hole (100) that is formed in said one (82b) of the pair of support walls coaxially with the second piston (92; 200), and in which the second piston is slidably and hermetically seated in oil, the second piston and the piston seating hole cooperate to define an oil chamber (102) . 7. Vehicle energy transmission system, according to claim 6, characterized by the fact that the Petition 870180014596, of 02/23/2018, p. 94/121 3/4 oil (102) is a cylindrical space formed coaxially with the rotating axis (44). Vehicle power transmission system according to any one of claims 1 to 7, characterized by the fact that a damping member (110) is interposed between the first and second pistons (90, 92), and the first piston ( 90) is maintained in adjacent contact with the second piston (92; 200), via the damping member, such that the first piston is rotatable relative to the second piston. Vehicle power transmission system according to claim 8, characterized in that the damping member (110) is connected to an axial end face of the second piston (92; 200) on the side of the first piston (90) . 10. Power transmission system according to claim 6 or 7, characterized by the fact that the hydraulic actuator (112) includes a mechanically operated hydraulic pump (41), or an electrically operated hydraulic pump, to pressurize a fluid operation in the oil chamber (102), to thereby axially move the second piston (92; 200) in a direction towards the first piston (90). Vehicle power transmission system according to any one of claims 5 to 7, characterized in that the rotary axis (44) has a central hole (44a) in which the first piston (90) and a terminal portion axial of the second piston (92; 200) are accommodated, and a lubricant is supplied in the central hole through one of the opposite axial open ends of the central hole which is on the other side (82a) of the pair of support walls (82a, 82b ), the clutch gear (54) being mounted on the rotary shaft, via a needle bearing (84), such that the clutch gear is rotatable relative to the rotary axis, the rotary axis having at least one radial oil passage (86 ) formed in order to extend through Petition 870180014596, of 02/23/2018, p. 95/121 4/4 of it in its radial direction, so that the lubricant is distributed from the central hole to the needle bearing through at least one radial oil passage. 12. Vehicle energy transmission system, according to claim 11, characterized by the fact that the rotary axis (44) has a guide hole (88) that extends in its axial direction, for fluid communication with the hole central (44a), and the sleeve (56) is connected to the first piston (90) through a connecting member (58) which extends through the guide hole, and which is attached to the first piston. Vehicle energy transmission system according to any one of claims 1 to 12, characterized by the fact that the first piston (90) is located in an axially average portion of the rotary axis (44). Vehicle energy transmission system according to any one of claims 1 to 12, characterized in that the first piston (90) is located on an axial end portion of the rotating shaft (44) which is on the side of the second piston (200).